Research completed in the past few years has demonstrated a causal relationship between cancer of the urinary bladder and Schistosoma haematobium infection. Although a potential for studies in parasite carcinogenesis has been established, the mechanisms involved are unknown. In the coming year more in depth investigations will be made in an effort to clarify the nature of schistosome infection and induction of bladder cancer. Accumulated data and information will provide a complete parasitological profile indicating host-parasite relationships in infected nonhuman primates. Materials obtained from infected subjects (capuchin monkeys) will allow further exploration on the relationship of experimental schistosomiasis haematobia and alteration of tryptophan metabolistes, significant factors in bladder carcinognesis. Also, there will be opportunity for more detailed evaluation of hisotpathology aspects of S. haematobium infection and bladder cancer in a long series of infected animals. Attention will also be given to the possible role of viruses as a co-carcinogen. Efforts will be made to exploit the potential offered by the model system (capuchin monkey (Cebus) - paraiste (S. haematobium) - cancer (urinary bladder)) developed in this laboratory.